1. Field
The disclosed technology relates to a pixel, a display device including the same, and a driving method thereof. More particularly, the disclosed technology relates to a pixel that is robust to a coupling or a leakage current caused by an external voltage, a display device including the same, and a driving method thereof.
2. Description of the Related Technology
An organic light emitting diode (OLED) display uses an OLED for controlling luminance by current or voltage. The OLED includes an anode layer and a cathode layer for forming an electric field, and an organic light emitting material electric field for emitting light by the electric field.
Generally, OLED displays are classified into one of two types: a passive matrix OLED (PMOLED) and an active matrix OLED (AMOLED) according to the driving circuitry.
Between them, in view of resolution, contrast, and operational speed, AMOLED drivers that are selectively turned on for every unit pixel find the most widespread commercial applications.
One pixel of an active matrix OLED includes an organic light emitting diode, a driving transistor that controls the amount of current that is supplied to the organic light emitting diode, and a switching transistor that transmits a data voltage that controls the driving transistor to adjust the amount of light that is generated by the OLED. The switching transistor is turned on by a scan signal of a gate-on voltage.
An OLED display may be operated with a simultaneous light emitting method in which all pixels simultaneously emit light after all pixels are programmed with data during one frame. The simultaneous light emitting method has merit in that it is not influenced by a voltage drop of a power source voltage due to wire length when programming the data.
However, this method has a short light emitting period compared with a sequential light emitting method in which a plurality of pixels sequentially emit light. Accordingly, to maintain the same luminance as in the sequential light emitting method, much current must flow to a plurality of pixels in the light emitting period. For this, the power output of a data driving IC (integrated circuit) must not only be expanded, but also a voltage difference between the power source voltage of both terminals of the pixel providing the driving current must be increased. If the voltage difference between the power source voltage of both terminals of the pixel providing the driving current is increased, the voltage drop caused by the wire is increased such that the power source voltage must be designed for the voltage difference between the power source voltage of both terminals of the pixel to have a margin of error.
Resultantly, the voltage difference between the power source voltage of both terminals of the pixel must be designed to meet this criteria, and accordingly power consumption is increased. Also, by considering the voltage drop of the wire length, although the power source voltage is set up or the voltage difference between the power source voltage of both terminals of the pixel is sufficient, uniformity of luminescence across the entire screen of pixels may decrease by the voltage drop of the power source voltage.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.